Unit 4, Lesson 25# Relate manipulative representations to a written method

EngageNY 60 min(s)

In this lesson, students deepen their understanding of subtraction by relating the concrete model of subtraction to the standard algorithm. They model decompositions on their place-value chart while simultaneously recording the changes in the written form. Students draw a magnifying glass around the minuend, then ask the question, "Do I have enough ones?" They refer to the place-value disks to answer and exchange a ten disk for 10 ones when necessary. They record the change in the vertical form. Students repeat these steps when subtracting the tens.